The work proposed in this application is designed to increase our basic and clinical knowledge of reproductive processes in the male with particular relevance to male contraception. In addition to our four main projects, we also propose continuing our Administrative Core, which coordinates the management of the center, including fiscal management of the research projects and the development program of new invesfigators. This core provides administrative support for all center activities, including meetings and seminar series, and makes arrangements for visiting scientists and trainees. The core will be equally responsible to each project and will consist of a program manager and a fiscal specialist. These key individuals will work closely with personnel from the NICHD and campus administrators at the University of Washington, Washington State University and the Jackson Laboratories to manage study funding and regulatory approvals. The administrative core also coordinates the monthly seminar series, monthly investigators meetings and other meetings as necessary. In addition, this core will assure smooth functioning and excellent outcomes for our Fellows and New Investigators Program.